Method for internal heating reformation by oxidation

ABSTRACT

A method of producing hydrogen by reforming a hydrocarbon or an aliphatic alcohol. The method includes preparing a columnar catalytic member having many axial passages and containing a reforming catalyst, a shift catalyst and an oxidation catalyst; preparing a reformable gas containing a hydrocarbon or an aliphatic alcohol and water vapor mixed together; rotating the columnar catalytic member, while passing the gas therethrough transversely with respect to its cross-section such that the gas first flows along a forward path extending in one direction through a first portion of the axial passages and then flows along a backward path extending in the other direction through a second portion of the axial passages, thereby causing the gas to undergo reforming and shift reactions to form hydrogen for recovery, while the gas makes a round trip along the forward and backward paths; and introducing an oxygen containing gas into the forward path and/or the backward path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of application Ser. No.10/204,199 filed Aug. 16, 2002, issued as U.S. Pat. No. 6,911,187, whichis a U.S. National Phase Application under 35 U.S.C. 371 ofInternational Application No. PCT/JP01/01136 filed Feb. 16, 2001, theentire contents of which are hereby incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a method of making hydrogen byreforming reactions as well as an apparatus for carrying out the method.

BACKGROUND ART

Methods and apparatus in a variety of forms have so far been known tomake hydrogen by reforming reactions. The practice with all theseconventional methods and apparatus was, however, to derive a heatnecessary for reforming reactions, simply from either the sensible heatof a gas burnt outside of the reforming reaction apparatus or a sensibleheat generated by a heating medium. As a result, the sensible heat comesto be supplied through the wall surfaces of the reforming reactionapparatus. Not only does this require the apparatus as a whole to belarge in size, but also its thermal efficiency is far from being wellsatisfactory. Furthermore, if a hydrocarbon is used as it typically ismethane requiring a heating temperature of 700 to 750° C. for itsreforming reactions, such an external heating system while requiringthat the wall surfaces of the reforming reaction apparatus be externallyheated at a temperature much higher than that temperature has requiredthat they be heated at a temperature below 1000° C. because if thetemperature of 1000° C. is exceeded, the material that makes up the wallsurfaces tends to deteriorate.

In order to dissolve such inconveniences in the prior art, the presentapplicant has already proposed in Japanese Patent Application No.2000-5843 an invention pertaining to an improved reforming reaction orreforming method and apparatus in which as a mixture gas of ahydrocarbon or aliphatic alcohol and water vapor is supplied andcontacted with a reforming catalyst, a small amount of oxygen is mixedin the mixture gas of hydrocarbon or aliphatic alcohol and water vaporin an appropriate stage and an oxidation catalyst is added to thereforming catalyst to oxidize a part of the hydrocarbon or aliphaticalcohol and thereby to liberate a heat so that the quantity of heatrequired for the reforming reaction is internally supplied.

While if an example is taken of the case with a hydrocarbon atemperature of 700 to 750° C. is required to terminate the reformingreactions as an endothermic reaction, it has been found that theimproved method in which heat is liberated by the oxidation reactionwithin a catalyst layer makes it possible to generate a sensible heatsufficient to maintain a temperature of 700 to 800° C. Thus, designed tointernally generate the heat and thereby making it possible to maintaina temperature in the range necessary for the reforming reactions, themethod makes it possible to render not only the apparatus markedlysmaller in size but also the thermal efficiency much higher comparedwith the prior art that relies on the external heating.

The present invention is a further improvement over the inventionmentioned above and is designed to further improve the thermalefficiency. And, it basically utilizes a technical idea found to improvethe thermal efficiency of a burning type de-odorizer as disclosed in JP2000-257837 A (Japanese Patent Application No. H11-59652), and appliesthe idea to the method of making of hydrogen by reforming reactions tofurther improve the thermal efficiency in the process.

The present invention is also to provide an apparatus for implementingsuch a method, the apparatus not only being of an improved thermalefficiency but also being possibly made further smaller in its entirestructure.

DISCLOSURE THE INVENTION

In order to achieve the objects mentioned above, the present inventionprovides a method of reformation which comprises the steps of: preparinga columnar catalytic member containing a reforming catalyst, a shiftcatalyst and an oxidation catalyst, the columnar catalytic member havinga multiplicity of axial passages; preparing a reformable gas having ahydrocarbon or an aliphatic alcohol and water vapor mixed together;rotating the columnar catalytic member while passing the gastherethrough transversely to its cross section in such a manner that thegas first flows along a forward path extending in one direction througha first portion of the axial passages which accounts for nearly one halfof the cross section and then flows along a backward path extending inthe other direction through a second portion of the axial passages whichaccounts for nearly the other half of cross section, thereby causing thegas to undergo reforming and shift reactions and thereby to give rise tohydrogen for recovery while the gas makes a round trip along the forwardand backward paths; and introducing an oxygen containing gas into theforward path and/or the backward path.

The method designed as mentioned above permits heat to be generatedmainly in the backward path by the introduced oxygen gas effecting anoxidation reaction there with the aid of the oxidation catalyst. Whilethe quantity of heat thus generated comes to heat the catalytic member,it follows that the rotation of the catalytic member displaces theheated portion to the forward path side, with the result that thisquantity of heat contributes to fresh reforming reactions in the forwardpath. Consequently, the quantity of heat required for reformation,eventually the quantity of oxygen consumed is made less in the presentinvention than in the previous invention by the present inventormentioned before.

The present invention also provides an apparatus for implementing themethod mentioned above, which apparatus comprises: a hollow cylindricalframe having its bottom closed; a columnar catalytic member having amultitude of axial passages, mounted in and supported by the cylindricalframe so as to be rotatable relative thereto by a drive means such as anelectric motor; a closure means closing an upper end of the cylindricalframe and making a space immediately above the columnar catalyticmember; a partition means for subdividing the space into a first and asecond independent space; a gas inlet port formed in the closure meansfor introducing a mixture gas of hydrocarbon or aliphatic alcohol andwater vapor into the first space; a hydrogen outlet port formed in theclosure means for recovering hydrogen generated from the second space;and an oxygen inlet port for introducing oxygen into a region of thecatalytic member, wherein the oxygen inlet port may make further use ofthe gas inlet port and/or be additionally provided for communicationwith a closed space at the bottom in the cylindrical frame.

In the apparatus constructed as mentioned above, while the heat ofoxidation reaction by oxygen primarily generated in the backward path inthe catalytic member tends to heat the backward path region of thecatalytic member, the rotation of the catalytic member by the electricmotor or the like repeatedly displaces the heated region to lie in theforward path side to make the generated quantity of heat available forfresh reforming reactions of fresh mixture gas replenished in theforward path.

Mention is made in detail below of specific features of the presentinvention.

While the gas used for the method of the present invention is either ahydrocarbon or aliphatic alcohol, the difference between them intemperature required for reforming reactions makes a large differencebetween the amounts of an oxidation catalyst used respectivelytherewith.

In the case of a hydrocarbon, a temperature of 700 to 750° C. isrequired to accomplish its reforming reactions. In the conventionalexternal heating reformer, the reforming reactions are made to commencewhen the mixture of the hydrocarbon and water vapor is externally heatedto have a temperature of about 500° C. and are virtually finished whenthe temperature is raised to 700 to 750° C.

Since the reforming reaction is an endothermic reaction, so that thereaction temperature in the reforming catalyst may not fall, enoughamount of heat commensurate with the endotherm must be suppliedexternally in the conventional reformer.

In the method of the present invention, however, the liberation of heatby the oxidation reaction in the catalyst layer generates a sensibleheat sufficient to maintain a temperature of about 700 to 800° C. and isthus capable of maintaining a range of temperatures required for thereforming reactions. Thus, if the low temperature hydrogen generated bythe reforming reactions tends to bring about a fall in the temperatureof the mixture gas of hydrocarbon and water vapor, then oxygen extant inthe mixture gas is allowed to react with hydrocarbon again with the aidof the oxidation catalyst in the catalyst layer and thereby to restorethe temperature of the mixture gas to about 800° C. so that thereforming reactions may repetitively continue. Thus, in the method ofthe present invention, a state is created as if a fine and multi-stagecatalytic combustion is taking place in the catalyst layer, whichlargely reduces the needed amount of the reforming catalyst and permitsthe reformer to be made small in size. The oxidation catalyst should beused contained in an amount that is 2 to 10% (in the case of methane,preferably in a range of 3% plus and minus 2%) of the amount of thereforming catalyst. For the oxidation catalyst, use may be made of anysuch catalyst that can withstand a temperature as high as mentionedabove, although commonly used is a dispersion of platinum, palladium orthe like in the reforming catalyst.

On the other hand, an aliphatic alcohol is much lower in reformingtemperature than a hydrocarbon and indeed has reforming reactions goingon at a temperature as low as 250 to 350° C. Moreover, its smallendotherm in reforming reactions makes it sufficient to supply themixture gas of aliphatic alcohol and water vapor with a reduced amountof oxygen. Consequently, the reformer can be made further smaller insize with an aliphatic alcohol. The proportion of the oxidation catalystin the case of an aliphatic alcohol may range from 1 to 5% (withmethanol, preferably 2% plus and minus 1%) of the amount of thereforming catalyst.

If a reforming catalyst is used having a space velocity (SV), forexample, of about 3,000, the use of an oxidation catalyst having a spacevelocity of about 100,000 may achieve the object, although it isimportant to ensure that the oxidation catalyst is sufficientlyuniformly dispersed in the reforming catalyst. It is then useful toprovide a very small layer of the oxidation catalyst in front of thereforming catalyst layer containing the oxidation catalyst to facilitatethe initiation of the reactions. Also, to expedite the completion of thereactions it is possible to provide a very small layer of the oxidationcatalyst behind the mixed reforming catalyst layer.

Hydrocarbon or aliphatic alcohol supplied into the reforming catalystlayer mixed with the oxidation catalyst reacts with oxygen with the aidof the oxidation catalyst whereby heat is liberated raising thetemperature of the mixture gas obtained. The thus heated mixture gas oncontacting the reforming catalyst undergoes the reforming reactions,thereby generating hydrogen. As mentioned previously, while thereforming reaction being an endothermic reaction lowers the temperatureof the mixture gas, the presence of the oxidation catalyst in thedownstream reforming catalyst layer as well permits an unreacted portionof hydrocarbon or aliphatic alcohol to further react with oxygen stillextant and thereby to liberate heat. With the temperature of the mixturegas thus maintained in the reaction temperature range, the reformingreactions are allowed to continue successively stepwise until oxygen inthe supplied gas is fully consumed. If the thickness of the reformingcatalyst layer through which the mixture gas is passed is set up so asto be commensurate with the feed rate of the mixture gas, it is thenassured that the reforming reactions are made complete at the exit endof the catalytic layers. In the interest of the protection ofenvironment, however, it is desirable that an acceptable small layer ofthe oxidation catalyst only be provided at the exit end of the catalyticlayers so that there is no residual oxygen there.

The oxidation catalyst and the reforming catalyst may be arranged inlayers, one top of the other. These layers may also be used as multipletiers spaced apart by a perforated support plate between them. It isalso possible to use the oxidation and reforming catalysts in the formof a mixed catalytic layer in which they are fully mixed together. Asregards the shift catalyst, it is typical to locate a layer thereofabove both of the oxidation and reforming catalyst layers so that theymay work after the reforming reactions have mostly or at least mostlybeen concluded. Also, to expedite conclusion of the oxidizing reactions,it is desirable that a layer of the oxidation catalyst only beadditionally provided at the uppermost end of the catalytic layers.

In a preferred form of the reaction apparatus, it is desirable toprovide between the first space connected to the reformable gas inletport and the second space connected to the reaction product (hydrogen)gas outlet port a third space narrower than these spaces and ascavenging gas inlet port connected to the third space for introducing ascavenging gas (usually a mixture gas of oxygen and water vapor,including no reformable gaseous component) into it. This arrangement isdesigned to cause the scavenging gas to act on such a portion of thereformable gas including an unreacted component that is being brought inthe backward path from the forward path as the catalytic member isrotated and to drive it out past passages in the catalytic membersdownwards into the bottom space in the apparatus so that the samereformable gas portion may be reformed by the reforming catalyst in thebackward path to conclude the reactions therein.

The SV value suitable for the reactions in the present invention mayrange between 1,500 and 8,000 for the hydrocarbon and between 2,000 and8,000 for the aliphatic alcohol.

What can be listed as the hydrocarbon usable includes methane (CH₄),ethane (C₂H₆), propane (C₃H₈), kerosene, gasoline and so forth, althoughusually used is CH₄. Then, the reforming reactions are effectedgenerally at a temperature between 750 and 800° C. And, what can belisted for the aliphatic alcohol includes methanol, ethanol and soforth, although often used is methanol. The temperature of the reformingreactions with the aliphatic alcohol ranges between 250 and 350° C.

The ratio of water vapor to hydrocarbon (H₂O/C) normally ranges between2.5 and 3.5. If hydrocarbon is replaced by aliphatic alcohol, the ratio(H₂O/C) usually ranges between 1.5 and 2.

The reforming catalyst that can be used here may be any reformingcatalyst that has hitherto been commonly used, although what can belisted as commonly used includes NiS—SiO₂.Al₂O₃, WS₂—SiO2.Al₂O₃, andNiS—WS₂.SiO₂.Al₂O₃. Included as the shift catalyst commonly used areFe₂O₃ and Fe₃O₄, but if reactions are to be effected at a temperature of700° C. or higher, then the use of a particular catalyst such as Cr₂O₃is preferable. The oxidation catalyst should preferably be Pt or Pd,which is hard to deteriorate at an elevated temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will better be understood from the followingdetailed description and the drawings attached hereto showing certainillustrative forms of embodiment of the present invention; in thisconnection, it should be noted that such forms of embodiment illustratedin the accompanying drawings hereof are intended in no way to limit thepresent invention but to facilitate an explanation and understandingthereof. In the drawings:

FIG. 1 is a longitudinal cross sectional view illustrating oneembodiment of the reforming reactor apparatus according to the presentinvention; and

FIG. 2 is a transverse cross sectional view of the apparatus taken alongthe line II—II in FIG. 1.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, an explanation is given in respect of a reforming reactorapparatus that represents a suitable embodiment of the presentinvention, reference being had to the accompanying drawings.

Referring to FIG. 1, the apparatus includes a hollow cylindrical frame 3made in the form of a receptacle having a cylindrical peripheral wall 1and a bottom wall 2 made in the form of a disk. Mounted in the innerspace of the cylindrical frame 3 is a columnar catalytic member 4 havinga honeycomb structure and its central part supported by a longitudinallyextending shaft 8 so that it is rotatable. The honeycomb like catalyticmember 4 is made of a honeycomb like passage member 4 a whose surfaceshave catalysts applied or otherwise attached thereto. The honeycomb likecatalytic member 4 has a size that is, for example, 150 to 1000 mm indiameter and then has a height of 600 to 4000 mm that is about 4 timesas large as the diameter. The shaft 8 at its upper portion is rotatablysupported by a lid body 5 which is attached to the cylindrical frame 3to close its top, and the shaft 8 is designed to be rotated by arotation drive unit 19 such as an electric motor disposed above the lidbody 5.

The honeycomb like passage member 4 a has a structure made up bybundling or tying up in a cylindrical bundle a plurality of honeycomblike passages or passage elements composed of a ceramic or metallicmaterial and open both upward and downward and reinforcing the lower endof the bundle with a supporting frame 10. A coiled spring members 9 isreceived in a space defined between the underside of the supportingframe 10 and a mounting fixture 11 fastened to the lower end of thesupporting shaft 8. The disk portions of the supporting frame 10 and themounting fixture 11 are both open up and down so that the lower end ofthe honeycomb like passage member 4 a communicates with the lowerportion of the inside space of the cylindrical frame 1. While in theembodiment illustrated the supporting shaft 8 is shown supporting thelower end of the honeycomb like passage member 4 a and supportedrotatably only by the lid body 5 mounted so as to close the top of thecylindrical peripheral wall 1 of the cylindrical frame 3, thecylindrical frame 3 may be made to support the lower end of the shaft 8with its bottom wall 2 as well.

Mention is made below of examples in size of the honeycombed passagemember 4 a.

TABLE 1 Ceramic made Metal made Number of cells (number) 400 600 Area ofcontact (cm²/cm³) 27.8 33.0 38.8 Open area ratio (%) 78 73 90.2 * Thenumber of cells indicates the number of holes per 1 square inch.

The term “honeycomb like passage member” is used here for the reasonthat an individual passage may have a cross section that is polygonalother than hexagonal, or even circular as the case may be, or can evenhave a sector structure with circumferentially subdivided sectors as thecase may be.

The lid body 5 has a portion 5 a secured to the peripheral wall 1 of thecylindrical frame 3, whose inner surface is adapted to have a peripheralregion of the top of the honeycomb like catalytic member 4 slidablycontacted thereto while hermetically sealing the top of the honeycomblike catalytic member 4. The lid body 5 is also bulged upwardsimmediately above the honeycomb like catalytic member 4 so as to formthere a space that communicates with the honeycomb like catalytic member4. This space as shown in FIG. 2 is subdivided by three partition walls12 a, 12 b and 12 c radially extending from around the shaft 8 to formthree mutually independent chambers, namely a gas inlet chamber 13, apurging or scavenging gas chamber 14 and a product outlet chamber 15,each in communication with the honeycomb like catalytic member 4. It iswith the lower ends of the three chambers: the reformable gas inletchamber 12 a, the scavenging gas chamber 12 b and the product outletchamber 12 c that a top surface of the honeycomb like catalytic member 4is made to slidably contact while being hermetically sealed by the lidmember 5. Referring to FIG. 2, the inlet chamber 13 and the outletchamber 15 are shown at the right and left hand sides, respectively,each having its horizontal cross section that is almost semi-circular insize, and the two being connected to the gas inlet port 16 and the gasoutlet port 18, respectively. The scavenging chamber 14 is in the formof a fan in cross section that is smaller in cross sectional area thanthe other chambers, and is provided with a scavenging or purging gasinlet port 17, which is supplied with a scavenging or purging gas thatmay be water vapor which unexceptionally contains oxygen to feed it intothe scavenging chamber 14. Each of the partition walls 12 a, 12 b and 12c has a wall thickness greater or not less than the right to left widthof a single honeycomb cell so that when the partition wall lies on thecenter of the single honeycomb cell with the rotation of the honeycomblike catalytic member 4 the single honeycomb cell is not exposed to bothof the right and left hand side of the partition wall to ensure that theadjoining chambers 13, 14 and 15 are not short-circuited one another viathe space above the single honeycomb cell.

The honeycomb like catalytic member 4 in the embodiment illustrated inFIG. 1 comprises a plurality of catalytic layers disposed axially fromtop towards bottom in the order of a layer of oxidation catalyst 20, alayer of shift catalyst 21, a layer of reforming catalyst 22 and a layerof oxidation catalyst 23.

Mention is next made of the operation of the embodiment constructed asdescribed above.

With the operation initiated, the scavenging chamber 14 is supplied witha scavenging gas such as water vapor unexceptionally containing oxygenfrom the scavenging gas inlet port 17. A mixture gas of hydrocarbon oraliphatic alcohol and water vapor that may optionally contain oxygen isintroduced from the gas inlet port 16 and in flowing downwards throughthe region of the honeycomb like catalytic member 4 shown in the righthand side in FIG. 1, first comes into contact with the oxidationcatalytic layer 20 where a part of oxygen in the gas provides anoxidation reaction, liberating a heat. The heat thus generated furnishesa quantity of heat required for a part of the hydrocarbon and watervapor in the course of passing through the reforming catalytic layer 22to initiate a reforming reaction. Oxygen still extant in the gasprovides an oxidation reaction in the oxidation catalytic layer 23 asthe lowermost layer of the right hand side part of the catalytic member4, thereby liberating a heat again. The gas of hydrocarbon and watervapor having thus in part undergone its reformation and containingoxygen if still extant arrives in the bottom space 6 in the cylindricalframe 3. In the process described above, rotating the honeycomb passagemember 4 at a speed of rotation, for example, of 20 rpm causes a portionof the gas before arriving in the bottom space 6 to tend to take its waytowards the left half of the catalytic member 4 as shown in FIG. 1. Inthis embodiment, however, such a portion of the gas tending to headtowards the left half is, before it actually reaches the left half,driven out downwards with the scavenging gas introduced via thescavenging chamber 14, shown in FIG. 2, from the scavenging gas inletport 17 as mentioned above. As a result, it is ensured that the entiregas midway of reformation necessarily arrives in the bottom space 6 inthe cylindrical frame 6.

Upon arriving in the bottom space 6 in the cylindrical frame 3, the gaswith a residual amount of oxygen under a pressure of the gascontinuously introduced through the inlet port 16 is passed upwardsthrough the region of the honeycomb like passage member 4 shown in FIG.1 as constituting the left hand side part. In this course, a heat isliberated by an oxidation reaction with a residual component of oxygenin the lowermost, oxidation catalytic layer 23 and is then expended toeffectively bring about a reforming reaction in the reforming catalyticlayer 22 immediately above it. Thereafter, the gas undergoes a shiftreaction in the shift catalytic layer 21, and a gas containing hydrogenas the final product of the process is recovered from the gas outletport 18. A heat is also liberated in the shift reaction. In themeantime, oxygen if still extant in the gas is used to react with anunconverted CO gas in a further oxidation reaction and thereby toproduce a CO₂ gas in the left hand side uppermost, oxidation catalyticlayer 20 as the final catalytic layer in the return path.

In any case, the heat produced by the oxidation reaction and/or by theshift reaction in the left half path in FIG. 1 is used to heat thehoneycomb like catalytic member 4. Since rotated, that heated part ofthe honeycomb like catalytic member 4 turns to the right hand side part,the heat is effectively utilized for the reforming reaction as anendothermic reaction carried out in the right hand side path in FIG. 1.

While a certain arrangement of catalytic layers is shown and describedabove, it will readily be appreciated by those skilled in the art thatthis, especially the placement of oxidation layers is merelyillustrative and they may be placed at various positions in the paths tothe extent that heat can be liberated for effective utilization inreforming reactions.

Also, using a portion of the oxidation catalyst to form an independentoxidation catalytic layer and a remainder oxidation catalyst in mixturewith the reforming catalyst to form a reforming or mixture catalyticlayer is advantageous in effecting a reforming reaction efficiently.

Further, as the occasion calls for, it is possible to supply water vaporalone from the scavenging gas inlet port 17 and to replenish oxygen intothe bottom space 6 from an oxygen inlet port 24 as shown in FIG. 2connected to the bottom space 6. Then, so replenished with oxygen, thegas under a pressure of the gas continuously through the gas inlet port16 is passed towards the top space through its path in thehoneycomb-like passage member 4 shown at the left hand side in FIG. 1and in this course the liberation of heat is effected by the oxidationreaction with the replenished oxygen component in the lowermost,oxidation catalyst layer 23.

It is also desirable to range the operating pressure for the reformingreaction between 4 and 11 kg/cm², and to pass the evolved product gasthrough an external membrane separator, thereby raising the hydrogenconcentration in and removing carbon monoxide from the product gas.

1. A method for auto-oxidation, internal heating reformation to producehydrogen, which comprises: preparing a columnar catalytic membercontaining a reforming catalyst, a shift catalyst and an oxidationcatalyst, the columnar catalytic member having a multiplicity of axialpassages; preparing a reformable gas comprising a hydrocarbon or analiphatic alcohol, and water vapor mixed together; rotating saidcolumnar catalytic member while passing said gas therethroughtransversely with respect to a cross-section of the catalyst member suchthat the gas first flows along a forward path extending in one directionthrough a first portion of said axial passages which accounts for onepart of said cross-section and then flows along a backward pathextending in the other direction through a second portion of said axialpassages which accounts for another part of said cross-section, therebycausing said gas to undergo reforming and shift reactions to formhydrogen for recovery, while the gas makes a round trip along saidforward path and said backward path; and introducing an oxygencontaining gas into one or both of said forward path and said backwardpath.
 2. The method as set forth in claim 1, wherein said catalyticmember has a reforming catalytic layer of said reforming catalyst, ashift catalytic layer of said shift catalyst and an oxidizing catalyticlayer of said oxidation catalyst, which are laid one on top of anotheraxially of said columnar catalytic member.
 3. The method as set forth inclaim 1, wherein said catalytic member has a mixed catalytic layer ofsaid oxidation catalyst and said reforming catalyst, and a shiftcatalytic layer of said shift catalyst, which are laid one on top of theother axially of said columnar catalytic member.
 4. The method as setforth in claim 2, wherein a portion of said oxidation catalyst formsanother oxidizing catalytic layer and a remainder of said oxidationcatalyst is contained in a mixture with said reforming catalyst.
 5. Themethod as set forth in claim 3, wherein a portion of said oxidationcatalyst forms another oxidizing catalytic layer and a remainder of saidoxidation catalyst is contained in a mixture with said reformingcatalyst.
 6. The method as set forth in claim 1, wherein said catalyticmember includes an oxidizing catalytic layer as a final catalytic layerin said backward path, whereby before said gas exits said backward path,any unconverted CO gas present therein is selectively oxidized into CO₂with oxygen still extant therein.
 7. The method as set forth in claim 2,wherein said catalytic member includes an oxidizing catalytic layer as afinal catalytic layer in said backward path, whereby before said gasexits said backward path, any unconverted CO gas present therein isselectively oxidized into CO₂ with oxygen still extant therein.
 8. Themethod as set forth in claim 3, wherein said catalytic member includesan oxidizing catalytic layer as a final catalytic layer in said backwardpath, whereby before said gas exits said backward path, any unconvertedCO gas present therein is selectively oxidized into CO₂ with oxygenstill extant therein.
 9. The method as set forth in claim 4, whereinsaid catalytic member includes an oxidizing catalytic layer as a finalcatalytic layer in said backward path, whereby before said gas exitssaid backward path, any unconverted CO gas present therein isselectively oxidized into CO₂ with oxygen still extant therein.
 10. Themethod as set forth in claim 5, wherein said catalytic member includesan oxidizing catalytic layer as a final catalytic layer in said backwardpath, whereby before said gas exits said backward path, any unconvertedCO gas present therein is selectively oxidized into CO₂ with oxygenstill extant therein.
 11. The method as set forth in claim 1, whereinsaid reforming reaction is carried out at an operating pressure of 4 to11 kg/cm², and the method further comprises a step of passing an evolvedgas through an external membrane separator to increase hydrogenconcentration and remove carbon monoxide from the evolved gas.
 12. Themethod as set forth in claim 2, wherein said reforming reaction iscarried out at an operating pressure of 4 to 11 kg/cm², and the methodfurther comprises a step of passing an evolved gas through an externalmembrane separator to increase hydrogen concentration and remove carbonmonoxide from the evolved gas.
 13. The method as set forth in claim 3,wherein said reforming reaction is carried out at an operating pressureof 4 to 11 kg/cm², and the method further comprises a step of passing anevolved gas through an external membrane separator to increase hydrogenconcentration and remove carbon monoxide from the evolved gas.
 14. Themethod as set forth in claim 4, wherein said reforming reaction iscarried out at an operating pressure of 4 to 11 kg/cm², and the methodfurther comprises a step of passing an evolved gas through an externalmembrane separator to increase hydrogen concentration and remove carbonmonoxide from the evolved gas.
 15. The method as set forth in claim 5,wherein said reforming reaction is carried out at an operating pressureof 4 to 11 kg/cm², and the method further comprises a step of passing anevolved gas through an external membrane separator to increase hydrogenconcentration and remove carbon monoxide from the evolved gas.
 16. Themethod as set forth in claim 6, wherein said reforming reaction iscarried out at an operating pressure of 4 to 11 kg/cm², and the methodfurther comprises a step of passing an evolved gas through an externalmembrane separator to increase hydrogen concentration and remove carbonmonoxide from the evolved gas.
 17. The method as set forth in claim 7,wherein said reforming reaction is carried out at an operating pressureof 4 to 11 kg/cm², and the method further comprises a step of passing anevolved gas through an external membrane separator to increase hydrogenconcentration and remove carbon monoxide from the evolved gas.
 18. Themethod as set forth in claim 8, wherein said reforming reaction iscarried out at an operating pressure of 4 to 11 kg/cm², and the methodfurther comprises a step of passing an evolved gas through an externalmembrane separator to increase hydrogen concentration and remove carbonmonoxide from the evolved gas.
 19. The method as set forth in claim 9,wherein said reforming reaction is carried out at an operating pressureof 4 to 11 kg/cm², and the method further comprises a step of passing anevolved gas through an external membrane separator to increase hydrogenconcentration and remove carbon monoxide from the evolved gas.
 20. Themethod as set forth in claim 10, wherein said reforming reaction iscarried out at an operating pressure of 4 to 11 kg/cm², and the methodfurther comprises a step of passing an evolved gas through an externalmembrane separator to increase hydrogen concentration and remove carbonmonoxide from the evolved gas.
 21. A method as set forth in claim 1,wherein said first portion of said axial passages accounts forapproximately one half of said cross-section and said second portion ofsaid axial passages accounts for approximately the other half of saidcross-section.